Hi Erik,
Here are the suggestions for the two questions:
1. Yes, the administrator can configure the FOPE to filter the spam in Office 365 E plan.
2. The user cannot access FOPE in Office 365 P1 plan. As a workaround, the users can set up the “Block or Allow” list in Outlook Web App to filter the spam. For more information about this function, please refer to http://help.outlook.com/en-us/140/ms.exch.ecp.junkemailconfiguration.aspx.
Thanks,
Eben Liu